Dermatitis is a superficial inflammation of the skin, characterized by vesicle formation, erythema, edema, oozing, scaling or crusting lesions, and intense itching. Different types of dermatitis can be distinguished: contact dermatitis, caused by irritants in contact with the skin or by non-irritating substances, to which the subject is allergic; atopic dermatitis, characterized by strong itching and chronic course; seborrheic dermatitis, a scaling disease mainly affecting the face and scalp. In principle, the treatment consists in removing the etiological agent; however, frequently such agent cannot be identified or removed.
One particular form of dermatitis is psoriasis, which is a chronic, inflammatory, hyperproliferative skin disease that affects approximately 1-2% of the general population with men and women affected in equal numbers (Nevitt, G. J. et al., 1996, British J. of Dermatology 135:533-537). Approximately 150,000 new cases of psoriasis and approximately 400 deaths from psoriasis are reported each year (Stern, R. S., 1995, Dermatol. Clin. 13:717-722). The impact of psoriasis on the lives of patients goes beyond the effects on their physical appearance; it can also negatively impact their physical capacity and longevity. The most common type of psoriasis is chronic plaque syndrome. The condition is chronic for many sufferers and consists of periods of remission and relapse during the course of the disease (Ashcroft, D. M., et al., 2000, J. of Clin. Pharm. And Therap. 25:1-10). Psoriasis is characterized by indurated, erythematous scaling plaques most commonly located on the scalp or the extensor aspects of the elbows and knees, but may occur at any skin site.
Traditionally, treatment of such dermatitis has been based on corticosteroids, which involves well known side effects such as reduced immune defense resulting in a secondary bacterial infection, particularly of fungi or Candida. Further, such treatment requires frequent suspension of the treatment, and such treatment cannot be used during the exudative acute phase of the dermatitis. Furthermore, prolonged use of corticosteroids should be avoided, especially in pregnant women and in children, as systemic side effects can occur.
The present treatment options currently available for psoriasis include topical agents, phototherapy and systemic agents. Topical treatments are first-line therapy for patients with mild to moderate plaque psoriasis. Systemic treatment is generally prescribed for severe cases of psoriasis where topical therapy is either impractical or ineffective. Phototherapy can be administered either alone or in combination with either topical or systemic agents. In selecting a suitable treatment, consideration should be given to the overall severity of the disease, the body areas involved, that patient's age, sex, general health, previous treatment and preferences.
Topical agents available for the treatment of psoriasis include emollients, keratolytics, coal tar, topical corticosteroids, dithranol (anthralin), topical vitamin D3 analogues and tazarotene. Unfortunately, these topical agents are associated with side effects such as irritation, toxicity and possible carcinogenicity (Ashcroft, D. M., et al., 2000, J. of Clin. Pharm. and Therap. 25:1-10).
Examples of phototherapy for psoriasis include ultraviolet B radiation (UVB) phototherapy and ultraviolet A photochemotherapy (PUVA). UVB phototherapy employs broadband (290-320 nm) sources and is useful in the management of moderate to severe psoriasis and is generally administered to patients whose disease is refractory to topical therapy. Treatment is usually administered two to three times a week with coal tar often being applied prior to exposure. UVB phototherapy must be carefully regulated, however, due to the short-term risks of erythema and vesiculation and the long-term risks or premature skin aging. PUVA therapy combines long wave (320-400 nm) ultraviolet A irradiation with oral or topical administration of psoralens. The two psoralens traditionally used, 5- and 8-methoxypsoralen (MOP) are believed to intercalate into DNA and inhibit cell proliferation upon activation by UVA radiation. PUVA therapy is generally administered twice weekly. Unfortunately, PUVA commonly causes short-term risks such as nausea, erythema, headache and skin pain as well as long-term risks of actinic keratoses, premature ageing of the skin, irregular pigmentation and squamous cell carcinoma which is reported in a quarter of patients (Stem, R. S., 1994, Cancer 73:2759-2764).
Systemic agents currently used to treat psoriasis include methotrexate (MTX), cyclosporin, acitretin and hydroxyurea. There are adverse side effects associated with each of these agents, however, and most are unavailable to pregnant patients. In particular, methotrexate, which is considered to be the ‘gold standard’ for treatment of severe psoriasis, carries a risk of hepatotoxicity with long-term use. In addition, it is recommended that patients have a liner biopsy performed at or near the start of each treatment and after each cumulative dose of 1.0-1.5 mg MTX (Roenigk, H. H. et al., 1988, J. of the Am. Acad. of Dermatology).
When patients are provided with information regarding the possible adverse effects of the currently available therapies for psoriasis, many often choose to live with the condition rather than undergo treatment (Greaves M. W., 1995, New England J. of Medicine 332:581-588). Other alternative treatments known in the art for dermatitis are based on hydrogenated vegetable oils, hydrophilic petrolatum, or medicated shampoos (based on zinc-pyrithione, selenium sulfide, sulfur and the like) in the case of seborrheic dermatitis, and are often unsuccessful.
In the case of the mucosal inflammatory conditions, in particular of mouth, gingival, rectal, vaginal and eye mucosae, a number of topical treatments are available, including the use of steroidal or non-steroidal anti-inflammatory agents, with the problems and side effects characteristics for these medicaments.
Different uses of proanthocyanidins have been described in the pharmaceutical and cosmetic fields. EP 0 694 305 discloses topical compositions of proanthocyanidins combined with coumarins (esculoside and the like) for the treatment of peripheral vasculopathies, such as bedsores, scars, couperose, varices and the like. U.S. Pat. No. 5,470,874 describes a combination of proanthocyanidins and vitamin C for the topical use, as sunscreen, for stimulating collagen synthesis and for restoring damaged collagen. Finally, JP 6,336,421 relates to topical formulations of proanthocyanidins combined with anti-inflammatories, among which glycyrrhetinic acid and derivatives are cited, for cosmetic use and against sunburns. However, to date the use of proanthocyanidins in the treatment of pathologies such as chronic dermatitis, seborrheic dermatitis and allergic dermatis has not been described.
Proanthocyanidins are widely diffused in a number of vegetable species. They are vegetable extracts containing bioflavonoids, with well-defined chemical profile, consisting for about 15% of dimers, about 20% of trimers and tetramers, and of small amounts of catechin and epicatechin. They also contain essential fatty acids similar to those of the skin hydrolipidic barrier, which contribute to keep said barrier intact. Finally, proanthocyanidins reduce the concentration of enzymes such as elastase, collagenase, hyaluronidase and beta-glucuronidase, which are responsible for the destruction of elastin, collagen and hyaluronic acid proteins. Therefore, proanthocyanidins are widely used in the pharmaceutical and cosmetic industries, thanks to their restoring, regenerating, nutrient and restructurant actions, which restores the skin elasticity and tonicity.
18-β-Glycyrrhetinic acid, extracted from the roots of Glycyrrhiza glabra, is known to have anti-inflammatory properties on the skin, in particular in bums and redness.
Telmesteine (N-carbethoxy-4-thiazolidinecarboxylic acid), described in Italian Patent No. 1,215,469, exerts antiradicalic and protective action against the oxidizing agents responsible for skin damages. Methods for making Telmesteine are described, for example, in U.S. Pat. No. 4,874,774 to Quadro, the disclosure of which is incorporated by reference herein in its entirety. Telmesteine, and alkali and alkali-earth of basic amino acid salts thereof, have anti-mucolytic activity and inhibit elastase and collagenase, and are known to be useful in the treatment of respiratory tract disorders such as emphysema and fibrosis.
There remains a great need in the art for therapies with improved activity than currently available drugs and treatment regiments for the prevention, treatment or amelioration of dermatological diseases and disorders such as dermatitis and psoriasis.
Citation or identification of any reference in Section 2 or in any other section of this application shall not be construed as an admission that such reference is available as prior art to the present invention.